Don't pull on it. You can seperate the butt from the rest of the body, and you push the blood back from its butt into your dog. If it's a tick it looks really full, and will fall off soon. Get yourself a tick tweezer, that way you hold the tick from its body and then twist it off without risk of pushing blood back.
Yeah I 2nd tick tweezers. I removed a lot of tick from shalter dogs and tick tweezers are so simple but efficient: just don't pull but rather, like state, twist it off!
Third tick tweezers. Olive oil can work in some, but definitely not all, cases. When you're done, drop it in rubbing alcohol (doesn't really matter what percent) and get a good picture in case your dog starts getting sick and has to go to the vet. A lot of vets can identify the type of tick and that can help narrow down treatments.
Watch for mood changes, appetite changes, lethargy, trouble getting around, or anything else that might indicate infection.
Get some preventative medicine if your dog is going to be running around in tall grass.